The present invention relates to a workpiece support apparatus and, in particular, a workpiece support apparatus suitable for use in welding complex branch structures.
One example of an application in which complex branch structures are welded is in the fabrication of piping for connecting various processing units in a processing plant. The piping generally consists of numerous primary or trunk lines having a myriad of secondary or branch lines. The secondary lines are fabricated to intersect the primary lines at varying angles and from varying elevations. The fabrication must be precise, or the piping will not line up during on site assembly.
What is required is a workpiece support assembly which can be used to support a workpiece during welding and assembly of such complex branch structure.
According to the present invention there is provided a workpiece support apparatus which includes an elongate primary body having several height adjustable primary support columns which extend vertically from the primary body. One or more arms extending radially from and are pivotally secured to the primary body. The arms pivot about a substantially vertical axis for angular adjustment on a substantially horizontal plane. At least two height adjustable secondary support columns extend vertically from each arm.
With the workpiece support apparatus, as described above, a pipe intended to serve as a primary or trunk line is supported on the primary support columns. A pipe intended to serve as a secondary or branch line is supported on the secondary support columns. The arm is adjusted to the correct angle of intersection of the trunk line with the branch line. The heights of both the primary support columns and the secondary support columns are adjusted to ensure that the intersection of the trunk line with the branch line is at the required elevation. With the workpiece support apparatus at the proper setting, the workpiece is held securely while the workpiece is welded to joint the branch line to the trunk line. As the complexity of the workpiece is increased, additional arms can be added to accommodate further branches.
Although beneficial results may be obtained through the use of the workpiece support apparatus, as described above, the positions at which support is required will vary to some degree with the configuration of the workpiece. Even more beneficial results may, therefore, be obtained when the some or all of the primary support columns and the secondary support columns are axially movable along the primary body. This enables the support columns to be positioned as required. The manner in which the support columns are made to be movable can vary. Beneficial results have been obtained by using tracks and providing each support column with a base that has rollers, as will hereinafter be further described; although other engagements may also be functional.
In order to avoid the need for manual adjustment, it is preferred that the support columns take the form of fluid activated telescopically extendible cylinders provided with fluid through fluid lines. In view of the number of support columns involved this creates a number of problems which have been addressed through series of innovations. In order to address the problem of supplying fluid to fluid lines which must be changed in length as the positioning of the support posts changes the fluid lines extending from each of the primary support columns are connected to a rotary fluid manifold. Upon rotation of the rotary fluid manifold in a first direction fluid lines are wound onto the rotary fluid manifold. Upon rotation of the rotary fluid manifold in a second direction fluid lines are fed from the rotary fluid manifold. Each support column as two fluid lines, an inflow line and an outflow line. In order to avoid having the fluid lines pinched or damaged, a plurality of direction altering rollers are used to route the fluid lines along the primary body and each of the arms. In order to avoid entanglement of the fluid lines, each of the fluid lines is segregated by means of radially extending dividers positioned on the rotary fluid manifold. In order to ensure that slack does not develop in the fluid lines which could result in them becoming pinched, rotation of the rotary fluid manifold is controlled by a spring loaded recoiler.
The quality of the final welds of the workpiece is, in part, dependent upon how precisely the workpiece is held by the workpiece support apparatus. Even more beneficial results may, therefore, be obtained when means is provided for levelling each of the primary support columns. Beneficial results have been obtained through the use of a screw levelling adjustment, as will hereinafter be further described, although other forms of levelling adjustment may also be functional. Even more beneficial results may, therefore, be obtained when means are provided for aligning each of the primary support columns axially along the primary body. Beneficial results have been obtained through laser alignment, although other forms of alignment may also be functional.
It is preferred that each arm be readily movable and be capable of being locked in the preselected position. Movement of the arms is effected by providing each arm with underlying rollers. Once in position, means are provided, in the form of locking pins, for locking the arms in a selected angular position. There is a limit to the amount of weight that rollers can bear. Even more beneficial results may, therefore, be obtained when each of the underlying rollers are spring mounted to a housing. The rollers have an extended position extending from the housing and a retracted position retracted within the housing. The rollers are normally in the extended position, however, the rollers assume the retracted position when a load is applied that overcomes the biasing force of the spring mounting.
Although beneficial results may be obtained through the use of the workpiece support apparatus, as described above, even more beneficial results may be obtained when each support columns has a top mounting adaptor adapted to receive a workpiece engaging member. This enables several alternative workpiece engaging members having differing support characteristics to be used, as will hereafter be further described. For example, with a pipe a xe2x80x9cVxe2x80x9d shaped workpiece engaging member is most appropriate. With a horizontal flange face, a table style workpiece engaging member is most appropriate. With a vertical flange face, a mounting bar attachment having projecting pins with adjustable pin spacing is most appropriate. In some situations, the workpiece engaging member may be in need of support. In such situations a rigidifying frame can be provided. Even more beneficial results may be obtained when each of the support columns has longitudinally extending grooves. These longitudinally extending grooves receive bars of the rigidifying frame to provide lateral stability to the workpiece engaging member when mounted on the top mounting adaptor.